Various functions in motor vehicles today are regulated or controlled by control units. For example, the ignition, fuel injection times and also the electrical power windows or the electrical sunroof are controlled or regulated by such control units. In automotive engineering today, there is an observable trend toward concentrating on a few control units with which numerous functions may be controlled. This concentration on a few control units is associated with a greater number of electrical contacts with which more actuators are controlled or regulated, and also more parameters are detected by sensors. Furthermore, the number of sensors installed is increasing steadily and these in turn require additional electrical contacts on the control units. Control units manufactured in the 1990s had far fewer than 100 contacts, but today it is standard for a control unit to have slightly less than 200 contacts. Efforts are presently underway to furnish control units with approximately 300 contacts.
Already today multiple contacts are combined to form one plug-in module having a plug housing, so that one control unit includes multiple plug-in modules. Accordingly, multiple electrical connectors which are compatible with the plug-in modules or the plug housings and are connected to a wiring harness are also required for detecting the parameters supplied by the sensors and/or for triggering the actuators.
The plug-in modules which are integrated into the control unit and connect the control unit to the sensors and actuators are designed in a plug connector assembly in which the plug connector assembly, which includes the plug-in modules, is manufactured in one piece, monolithically, so to speak, by the plastic injection molding method.
The electrically conductive contacts connecting the printed circuits present in the control unit to the plug connectors of the wiring harnesses are designed as pin contacts made of metal. To manufacture the finished plug connector assembly, the pin contacts are inserted into the injection mold and are sheathed with plastic during the injection molding process. The pin contact protrudes approximately 8 mm out of the plastic surrounding it in the direction of the plug connector. The opposite side of the pin contact is usually bent at an angle for reasons of space and is contacted directly to the printed circuit. Each plug connector assembly is therefore manufactured in accordance with the layout of the printed circuits encompassed by the control units.
On the part of automobile manufacturers, there are strict requirements on the plug connector assembly to be met by the control unit manufacturers. The individual contacts which extend in the direction of the plug connector and are combined to form a plug-in module must provide a position tolerance of 0.4 mm at their contact tips. On the other side, there is an effort on the part of the control unit manufacturers who want to ensure that the contact tips of the contact elements facing the printed circuits are precisely positioned, so that there is no problem with the tips finding the receptacles provided for them on the printed circuits.
Unforeseeable warpage may occur with the plug connector assembly because of the large amount of metal due to the electrical contacts and the irregular distribution within the plug connector assembly as well as the associated possibility of differences in cooling of individual areas inside the plug connector assembly. To be able to meet the tolerances as stipulated above and nevertheless be able to manufacture the plug connector assemblies in a fully automated manner, extensive reworking on an injection molding tool is required after it has been manufactured, thus causing substantial costs.